A novel method for preparation of hollow and solid carbon spheres

Hollow and solid carbon spheres were prepared by the reaction of ferrocene and ammonium carbonate in a sealed quartz tube at 500°C. The morphology and microstructure of the product were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The carbon spheres are amorphous and their diameters range from 0·8–2·8 μm. The shell thickness of the hollow carbon spheres is not uniform and ranges from 100–180 nm. It is suggested that ammonium carbonate is crucial for the formation of carbon spheres and its amount also influences the morphology of the product. The method may be suitable for large scale preparation of carbon spheres.     

A facile approach to fabrication of PbS hollow spheres with improved polystyrene templates

This paper provides a simple route to produce monodisperse PbS hollow spheres by using cationic polystyrene (PS) micro-particles as templates. The templates used in our experiment, were prepared via emulsifier-free polymerization by using the cationic monomer 2-(methacryloyloxy) ethyltrimethylammonium chloride as co-monomer. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTRI) were used to characterize the structure of the obtained PbS/PS composites and hollow PbS spheres. It was found that the as-produced samples are well-defined core-shell structures with an average diameter of about 0.98 μm. TEM showed that after the removal of the templates, the hollow structures were perfectly retained.     

A facile method to fabricate a series of micrometer scale hollow silica spheres

Hollow silica spheres (HSS) with the controllable diameters of 1.0 to 5.0 μm were successfully synthesized by adjusting the initial doubly distilled water volume in mixed ethanol-water solvent based on a complex approach that dispersion polymerization coexisted with a sol-gel process. The size of the HSS was uniform and the surface of the shell was smooth as observed by SEM. The FT-IR spectrum indicated that the inside core was completely removed. The thermal property and the compositions of core-shell spheres were investigated by TG-DSC.     

Synthesis of hollow spheres with mesoporous silica nanoparticles shell

Hollow spheres with mesoporous silica nanoparticles shell were synthesized with the use of cetyltrimethylammonium bromide (CTAB) and polystyrene (PS) hollow spheres as dual templates. The key to this study is that the uneven surface of the template provides nucleation sites for mesoporous nanoparticles, resulting in the formation of hollow spheres with mesoporous silica nanoparticles shell. The final products with hierarchical mesopores can be obtained through a simple one-step approach.     

A facile method to synthesize hierarchical SiO2@CdSe and CdSe hollow spheres

In this paper, a facile method was developed to synthesize SiO₂@CdSe particles by using silica colloidal spheres which efficiently avoided complex prior surface modification. In the experiment, ammonia was introduced to activate silica colloidal spheres with negative charge, which acted as active sites for the nucleation of CdSe nanocrystals around silica colloidal spheres. Then the corresponding CdSe hollow spheres were obtained by dissolving the silica cores. The TEM results exhibited CdSe hollow spheres were consisted of nanorods. On the basis of experimental results, the formation process of the hollow spheres was studied and possible growth mechanism for one-step coating process was proposed.     

Fabrication of nanoscaled silica layer on the surfaces of submicron SiO2-Ag core-shell spheres

A two-step silica deposition process, including prefunctionalization with poly(vinylpyrrolidone) and the following silica deposition, has been used to fabricate silica layer on the surface of nanoscaled silver shell. The influencing parameters of silica coating process were optimized to prevent the precoated silver nanoparticles from desquamating from silica spheres, finally to obtain mono-dispersed silica spheres with silver and silica multilayer films. The resulted silica layer was dense and uniform, its thickness was controllable in the range of 20–50 nm. Such coated silica layer can provide improved thermal stability of the SiO₂-Ag core-shell structural spheres.     

Fabrication of Nickel hollow spheres by microemulsion-template-interface reaction route

Ni hollow spheres (NHSs) have been successfully synthesized through a microemulsion-template-interface reaction route. The structures of NHSs were characterized by X-ray powder diffraction (XRD), selected area electron diffraction (SAED), transmission electron microscopy (TEM). The results showed that the size of the NHSs was between 50 to 150 nm. The shell thickness of the NHSs is about 20 nm. In our method, the metal precursor and reducing agent dissolved in two different phases; they can react at oil/water interface. Thus, hollow spheres can be fabricated more easily.     

A simple one-step fabrication of micrometer-scale hierarchical TiO2 hollow spheres

Hierarchical TiO₂ hollow spheres had been prepared based on bubble templates by a simple one-step hydrothermal method. The diameter of hollow spheres was about 700 nm and the shell thickness of them was 69 nm. They were composed of similar spindle- or needle-like building units. Furthermore, hydrothermal time had an important influence on the morphology and crystallinity of hollow spheres. Moreover, the UV-Vis diffuse reflectance spectra of TiO₂ hollow spheres heated at 150 °C for 10 h showed the strongest absorption in the UV-Vis region and the Raman spectrum demonstrated the anatase sample. Additionally, a possible formation mechanism of TiO₂ hollow spheres was proposed. So this novel and simple method would provide a development direction to fabricate all kinds of inorganic hollow spheres by one-step procedure.     

Simple synthesis of hollow carbon spheres from glucose

Hollow carbon spheres were prepared by the reaction between glucose and Zn particles at 550 °C. Scanning and transmission electron microscopies reveal that most of the spheres are about 1-2 µm in diameter, similar to the sizes of the Zn particle. The shells of the spheres are comprised of numerous hollow nanospheres with the diameter of 10-100 nm. The specific surface area of the spheres is 207 m²/g. The Zn particles act as both the reactant and the template for the micron-scale spheres, and the H₂ bubbles generated during the reaction as the template for the hollow nanospheres.     

Phosphonic acid-functionalized hollow silica spheres by nitroxide mediated polymerization

A new strategy to prepare phosphonic acid-functionalized hollow silica spheres is proposed via nitroxide mediated polymerization of diisopropyl p-vinylbenzyl phosphonate on the surface of hollow silica spheres (HSSs) and hydrolysis thereafter. The thickness of the organic layer of PVBPA can be controlled by the quantity of the monomers. The structure and morphology of poly(vinylbenzyl phosphonic acid) (PVBPA) grafted HSSs (HPSSs) are confirmed by FTIR and TEM. The addition of HPSS in PVBPA membranes can improve the water retentivity of the composite membranes. The composite membranes with HPSSs exhibit higher water uptake and proton conductivity than the pure PVBPA membranes.     

Synthesis of hollow silica spheres SBA-16 with large-pore diameter

Hollow silica SBA-16 spheres with cubic ordered mesoporous shells were synthesized by an emulsion-templating method, using Pluronic F127 as a structure-directing agent, tetraethyl orthosilicateas as a silica source and heptane as a cosolvent in the presence of NH₄F. The size of these spheres is in the range of 10 to 30 μm. The shell is about 700 nm thick and consists of large pores, ~ 9 nm in diameter, arranged in a cubic order. After calcination, the spheres maintain their mesoporosity and show a high surface area of 822 m²/g. The formation mechanism of the silica hollow spheres is discussed.     

基于物-场模型的纳米空心镍球的制备方法研究

针对目前混镍粉电火花腐蚀制备纳米空心镍球,存在着蚀除电极金属液滴与工作液中的小气泡不能充分结合,形成中空结构的问题,采用创新设计方法及知识库进行解决.根据实际工况,构建问题物 场模型,在知识库中搜索多种场,获得相应的解决方案.运用模糊评价法对多种方案进行评价与排序,挑选出最优方案--采用超声波场代替原有的机械场,开发出超声波制备纳米空心镍球装置,较好地改善了原有系统制备空心镍球的质量和效率.     

Synthesis and photocatalytic oxidation properties of titania hollow spheres

The hollow spheres of anatase TiO₂ with higher photocatalytic activity have been fabricated by spherical CaCO₃ nanoparticles as a template, and titanium sulfate (Ti(SO₄)₂) as a precursor, and the CaCO₃ templates were dissolved subsequently in dilute HNO₃ solution. The TiO₂ hollow spheres samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N₂ adsorption-desorption isotherms. The characterization results indicate that as prepared TiO₂ hollow spheres sample was transformed to anatase phase in calcined at 400 °C, and the anatase TiO₂ hollow spheres have a higher specific surface area and show much better photocatalytic activity than commercial P25 in the photodegradation of Rhodamine B under the UV irradiation.     

A dual template method for synthesizing hollow silica spheres with mesoporous shells

PS/silica core/shell composites were synthesized by the modified Stöber method using polystyrene spheres and cetyltrimethylammonium bromide as dual templates under room temperature. The silicate species and the templates were self-assembled to form mesoporous silica shell on the surface of the PS spheres. Hollow silica spheres with mesoporous shell were obtained by removing the polymer core and the templates through calcination. The hollow silica spheres showed high specific surface area of 1099.5 m²/g and narrow pore size distribution centered at 2.31 nm.     

A facile synthesis method for millimeter polyacrylonitrile-based activated carbon spheres with radiate tunnel-like macropores

A facile approach was employed to prepare polyacrylonitrile-based activated carbon spheres (PAN-ACS) through Rayleigh instability, double diffusion and catalytic activation. The obtained PAN-ACS were characterized by nitrogen adsorption-desorption and scanning electron microscopy (SEM). PAN-ACS had a better sphericity, and its average diameter was about 1.75 mm. And it displayed a novel hierarchical porous structure, in which macropores were tunnel-like and meso- and micropores existed in the wall of tunnels. The diameter of the tunnels was about 10 μm. And the tunnels arrayed regularly, radiating from the core. The distribution peak of mesopores mainly located at about 4.0 nm.     

NixFe3-xO4包覆空心玻璃微球的铁氧体化学镀制备及性能

采用铁氧体化学镀技术,在空心玻璃微球表面包覆了一层NixFe3-xO4膜,并采用X-射线衍射仪,扫描电子显微镜和电子能谱对其进行了表征.空心玻璃微球表面薄膜的厚度约为0.5微米,具有非晶结构.反应物的比例以及制备条件能够影响所制备铁氧体薄膜中镍和铁的比例.振动样品磁强计研究结果表明退火后样品显示铁磁特性.     

The sol-gel preparation of ZnO/silica core-shell composites and hollow silica structure

Three kinds of different ZnO colloid particles (flowerlike particles, nanoribbons and microspheres) and one kind of ZnO film have been coated with silica via a simple sol-gel method in the Stöber system and ZnO/silica core-shell microparticles or films have been obtained. The thickness of silica shell can be controlled by adjusting the concentration of TEOS added into the system. If the ZnO core is etched off by HCl, corresponding, hollow silica particles or film will be generated.     

Preparation of submicrometer-sized titania hollow spheres by templating sulfonated polystyrene latex particles

Submicrometer-sized titania hollow spheres with tunable shell thickness and smooth surfaces have been successfully synthesized by employing sulfonated polystyrene (PS) latex particles as a template in sol-gel method. The structure of the particles was characterized by scanning electron microscopy and transmission electron microscopy. The shell thickness was readily tuned by altering the concentration of titanium tetrabutoxide (TBOT) in ethanol solutions. The surface roughness as well as the shell thickness has the tendency to increase with the increase in the concentration of TBOT. The diameter of the hollow spheres was on the average of 20-26% smaller than the diameter of template PS latex particles. Some titania fragments were also observed for the sample with the highest TBOT concentration.     

二茂铁与氯化铵用量对气压法制备炭空心球直径的影响(英文)

研究了二茂铁和氯化铵的用量对气压法制备炭空心球直径的影响.炭空心球的形貌与直径通过场发射扫描电镜表征.实验发现:炭空心球的直径主要分布在1 μm ～10 μm,形貌基本一致.在二茂铁与氯化铵质量比一定时,炭空心球的直径随着原料总量增加而增大.当氯化铵过量时,炭空心球的直径存在双峰分布,但中位径基本不变.在合成过程中,铁颗粒与液态Fe(NH3)2Cl2模板的团聚,以及铁铵络合物之间的相互转化是影响炭空心球直径的主要因素.     

Spherical mesoporous silica templated with ionic liquid and cetyltrimethylammonium bromide and its conversion to hollow spheres

Spherical mesoporous silica was synthesized using a mixture of 1-methyl-3-octylimidazolium chloride and cetyltrimethylammonium bromide as the structure-directing agent. The obtained silica was characterized by X-ray powder diffraction, scanning electron microscope, transmission electron microscope, and ¹³C NMR spectroscopic techniques. The results show that the spherical silica possesses worm-like mesopores and larger mesopores, with the sizes about 6-50 nm. It is very interesting that the spherical mesoporous spheres were converted to hollow ones after reflux in boiling water. The treatment results in the generation of the hollow interior by dissolving the silica core. Meanwhile, the silica shell is well retained, which is confirmed by SEM and TEM images.